set size 1,1
      set origin 0,0
      set multiplot layout 3,1 columnsfirst scale 1,1
      
      

plot "test.txt" using 1 with lines, \
"test.txt" using 2 with lines, \
"test.txt" using 3 with lines

plot "test.txt" using ($2-$1) with lines

plot "test.txt" using 4 with lines, \
"test.txt" using 5 with lines, \
"test.txt" using 6 with lines   
unset multiplot